Method and apparatus for drying sheet material



7 Aug. 10,1926. 1,595,231

0. MINTON METHOD AND APPARATUS FOR DRYING SHEET MATERIAL Original'Filed Jan. 8. 1920 5 Sheets-Sheet 1 O. MINTON METHOD AND APPARATUS FOR DRYING SHEET MATERIAL EE L W Original Fild Jan. 8. 1920 5s s 2 l I00 4 A E o 5 7 5 i Aug. 10 1926.

0. MINTON METHOD AND APPARATUS FOR DRYING SHEET MATERIAL Original Filed Jan.

8, 192 5 Sheets-Sheet 4 a I a awn/MW? 7/11/71 1 A Q lE/l/ 7 I guom cqz abtome'q a Aug. 10 1926.

O. MINTON METHOD AND APPARATUS FOR DRYING SHEET MATERIAL 5 Sheets-Sheet 5' 'Original Filed Jan. 8, 1920 INVENTOR OGDEN MIN TON masm /a ATTORNK Patented Au 10, 1926..

- UNITED STATES 1,595,231 PATENT OFFICE.

OGDEN HIDITON, OF GEEENWICH, CONNECTICUT; METHOD AND AIEPARATUS FOB DRYING SHEET MATERIAL.

Continuation of application This application is a continuation of my companion application Ser. No. 350,234 for method and apparatus for drying sheet material filed Jan. 8, 1920; and it also embodies the broad claims of the inventions illustrated, described and claimed in my two co-pending applications Ser. No. 350,235 for method and apparatus for dr ing sheet mate-' rial filed Jan. 8, 1920; and .er. No. 350,236 1 filed Jan. 8, 1920 for method and apparatus for drying sheet material. It is, therefore,

the parent case from which the two species,-

claimed in Ser. No. 350,235 and Ser. No. 350,236 have been divided oilt.

The present invention relates to an apparatus and method for the drying of paper and other sheet materials.

My improved method consists in passing the sheet material, which is to be dried, into a vacuum chamber through a liquid sealing medium which has no aflini'ty for the material, subjecting it to heat to drive ofi its contained moisture and then passing the dried material out of the chamber through chamber, thelat er is provided with open ings closed to the admission of air by a 7 liquid sealing medium which has 'no aflinity for the material. The liquid seal effectively closes the entrance and exit passages against the admission of air to the chamber, but 4 out of the chamber. The heatin 1 elements within the Vacuum chamber, for rying the material, the shape, form, dimensions and location of the liquid seal containers, and the means for "passing the sheet material through the chamber, may all vary. shown herein a number of varieties which I contemplate using.

My mventionj further relates to drying sheet material at low temperature while under little or practically no .tension so that the fibers or constituent elements of the sheet material can. shrink at will or at random. That is the tension upon the sheet material .while it isdrying in thevacuum chamber is not sufiicient to cause the constitpermits the passage of the material into and I have Serial in. 350,234, and mas a, 1020. run. application filed November 17, 1920, Serial. No. 424,601.

Renewed July 9, 1926.

uent elements of the sheet material to materially rearrange themselves as they would have to do if they were dried under appre ciable tension. I My invention more particularly relates to continuously drying in a vacuum chambera wet web of paper as it comes from the wet end of a paper machine, or from a sizing vat, .or from-a coloring apparatus, coating machine or printing machine, or directly from a roll of wet paper so that the web will be continuously dried under little or no tension, the tension not beingsuflicient to cause the constituent fibers of the paper .to materially rearrange themselves fromtheposition thatthey assumed on the wiremesh 1n the paper machine during the making of the wet web. Or, which .is the same thing, the tension onthe web of paper to feed 1tcontinuously through the vacuum chamber isnot sufficient to prevent the fibers of the paper drying at random.

By my invention the web.'or sheet of paper cut from the web, will be substantially as strong lengthwise of the web or sheet as it is across the web or sheet;

My invention further relates to the manufacture of imitation 'hand made paper, and also to imitation loft dried paper. V j

My invention further; relates to varying the "cockeled effect in my imitation ha (1 made and imitation loft dried aper to 'uit difierent demands of the trade for these different papers.

My invention further relates to continu ously' passing the web of paper into and out of a vacuum chamber without breaking the vacuum; and heating and drying it in the: vacuum chamber in any suitable manner whereby the fibers of the paper are per-' mitted to dry substantially as formed on the wire mesh of the paper machine. I have shown, by way of example, three difl'er'ent ways of d ing the web in the vacuum chamber. the referred form the web' is continuous] fe through aheated bath of some liqui which has no aflinity" for or deleterious efiect upon the web. Such a.-

bath may be mercury, amalgam or some similar material having the characteristics above specified. I The other ways which I have shown are-to pass the web, while in the vacuum cham'-' ber adjacent to but not in contactwith fixed heated radiators, or adgaeent' to "electric heaters; Any other suita le heating means in the vacuum chamber may be employed which will dry the continuously fed web of paper and still not weaken it by causing its fibers to rearrange themselves.

My invention further relates to manufacturing paper wherein the size, if the paper has been sized before drying, is not injured or damaged due to the low temperatures at which I carryout my improved method.

My invention further relates to manufacturing colored paper and drying it without substantially impairing the coloring matter and mordants used in the paper. other advantages this insures that the paper will have bright colors which will be substantially uniform in different runs of paper; permitting matching of colored paper wthout any appreciable difference in tone or color.

My invention further relates to continuously passing the web of paper through the vacuum chamber in loops or folds and while under only sufficient tension tofeed the web through said chamber, and heating oneor more of said loops.

\My invention further relates to certain steps, and combinations of steps, also to certain elements and combinations of elements, whereby the method or processes herein described may be carried out, as well as to certain details of construction and combinations all of which will be more fully hereinafter described in the specification and pointed out in the claims.

The accompanying drawings, which are partly diagrammatic, illustrate several, but

not the only, forms of my apparatus, by the.

the product passing through the bath with in the vacuum chamber;

Fig. 4 1s a vertical diagrammatic section, similar to Fig. 3, but showing different size drums or rolls which will vary the finishing effect or smoothness of the sheet material passing through the bath within the vacuum chamber.

Fig. 5 is a vertical diagrammatic section of another form of apparatus in which the web is fed through the vacuum chamber in folds or loops adjacent to,-but not in contact with, fixed steam radiators;

Fig. 6 is a vertical diagrammatic section Among of still another form of apparatus which I may employ and in which fixed steam radiators are used;

Fig. 7 is a ve-rtical diagrammatic section of still another form of apparatus in which I employ glowing elements, as electric heat ers, past which the web of paper is continuously fed while under only sufficient tension to insure its passage through the vacuum chamber;

Fig. 8 is a vertical diagrammatic section of still another form of apparatus which I may employ and in which glowing elements, as electric heaters, may be employed.

Fig. 9, is a sectional view showing the terminal wire connected with the electric heater elements;

Fig. 10, is a sectional view of one form of regulator for rolls.

In describing my invention I will describe it as applied to sheet material in the form of paper, though it is to be distinctly understood it is equally applicable to, and covers drying sheet material in the form of textilefabric, as for example, drying such fabrics after they have been washed, or bleached, or dyed, or otherwise treated with a liquid of some description.

In the ordinary drying of a web of wet paper such high heat is used as to injuriously affect the fibers of the paper, and in case the paper is coldred it will adversely affect the coloring matter and mordants used. Drying paper in the high temperatures used in ordinary practice often affects the size so that the resulting paper varies in quality, is not uniform, and is not a perfect product.

My method possesses many advantages not present in processes heretofore used for many years in the drying of paper.

The evaporation process, which is characteristic of the so-called loft drying of paper, has many fully recognized disadvantages, and yet it is used today and has been in use for many years. In this method the wet paper is taken from the paper machine, cut into sheets, hung on poles, carried to the drying room where it is subjected to hot air at about 130 F. for about 48 hours, and when dr each sheet is separately calendered. lthough possessing the advantage of drying at a comparatively low temperature, whereby the moisture is slowly evaporated, loft drying is obviously very inefficient and costly, because it requires many separate manipulations, is extremely slow,

uses extensive floor space and wastes heat.

The process which is employed in the ordinary paper machine in common use, is

likewise subject to many disadvantages. In

such machine, the wet paper asit comes from the paper machine, is passed over many revolving cylinders, heated internally by steam to sufficiently high degree of heat, to raise the temperature of the water in the paper to 212 F.,'the atmospheric boiling pomt of water. It is customary tosupply the drying cylinders with steam at approximately 5.3 pounds gauge pressure, at which the steam has a temperature of228 F., giving a difference of temperature (228- 212) of only 16 With this slight difference of temperature the transfer of heat is extremely slow, and hence it is necessary to employ many drying cylinders, in board machines often one hundred, and in news print machines, forty or more.

Also due to convection and conduction losses, as well as those incident to leaks in the piping system and other inefiiciencies, the heat actually required for atmospheric drying of a ton of wet paper, is very much in excess .'of the theoretical requirement. The thermal efficiency of atmospheric drying by steam heated cylinders is thereforevery low. Furthermore, the steam pro- 1 duced from boiling the water out of the paper, is driven off into the operating room,

and although fans and exhausters are employed, at large expense for power and maintenance, the room atmosphere. is so constantly saturated with moisture as to rust and ultimately destroy all iron and steel materials, and produces an exceedingly disagreeable and unhealthy atmosphere in which to work. It is well known that the minimum temperature 212, ,the atmospheric boiling point of water, is positively injurious to, and results in oxidizing, the fibres of the paper, the strength of which is vastly 1 improved when the paper is dried at lower temperatures, as in left drying. This atmospheric drying process requires large initial cost for cylinders, felts, and other necessary equipment, and extensive floor space, and results in the consumption of large amounts of power, and great cost for operation, maintenance and repairs;

In my improved vacuum drying method I contemplate maintaining within the chamher a vacuum of about 28" of mercury, in which water boils at 100 F., and supplying the drying cylinders with steam at 5.3 pounds gauge pressure, producing a temperature of 228 F. The temperature difference between the temperature of the steam in the cylinders and that of the paper,

is therefore, 128 F. in my vacuum method,

or 8 times greater (16 F. X 8=128 F.) than the temperature dlfierence in atmospheric drying.

The thermal efiiciency of my vacuum method is very much greater than that of the atmosphericc linder drying heretofore in universal use or drying paper. Theo-.

retically, it requires about 5287 pounds of steam to dry one ton of paper at atmospheric pressure,but to compensate for convection and conduction losses, and those due to leaks in the pipingsystem, and other ineflimai ciencies, it has been shown in practice that about 10,600 pounds arerequired.

In my method, using avacuum of about 28", the convection, conduction and piping losses are exceedingly small and the total steam required to dry a ton of paper by my method'is approximately 5200 pounds.

It is an established fact that paper dried at low temperatures is much stronger than when it is dried at the high temperatures used in paper machine atmospheric drying. Paper dried in a vacuum of 28", or at a temperature of about 100 F., as. in my method, is very much stronger than paper dried at atmospheric pressure, when the steam in the driers is at 228 F. When paper is dried by my method, therefore, a cheaper furnish or stock can be used and still produce a paper equal in strength'to atmospheric dried paper, in which a higher grade furnish or stock-is used- In making newsprint paper, I am able to dispense with a considerable portion of the more expensive sulphite pulp, as this can be replaced with the cheaper ground wood pulp.

Furthermore, in my method there is a great saving of heat (orsteam) because the process is carried on in a vacuum chamber which acts on the principle of a thermos I bottle, and the steam and vapors driven out of the wet paper are caught in the closed vacuum chamber, and conducted away to p the condenser. The operating room is free process nowin common use, the web or sheet of paper is materially weakened. When the.

wet web of paper passes over-the steam heated dryers or cylinders the fibers of the paper areplaced under considerable tension 1n the direction of travel of theweb' and are not. allowed to dry as they were-interlaced or formed on the wire mesho'f the pa r machine. This stretching takes place wdi en the paper lies on' the cylinders or dryers and as heat is appliedthe paper'starts to shrink.

As the paper is held'tightl on the c linder by tension in itself as .we 1 as by t e fact that wet pa er clings to such a surface the shrinkage a takes lace across the sheet.

Paper measured on't efirst drying cylinder where wet, and on the last (1 in cylinder where dry, will show a consi era 1e -reduc-. tion in width proving the above statement.

The fibers have been pulledout into straight lines making the paper stronger across the sheet than lengthwise of the sheet.

Tocompensate for this'weakening of the web by pulling'the' fibers in the direction of travel of the web, it is customary in the old process now in use as previously noted, to employ a larger quantity of better furnish or stock than would otherwise have to be used. All furnish or stock is expensive. The better grades are much more expensive than .the inferior grades.

It will therefore be seen that under the old process a dry web of paper, which has been heated as high as 212 F. has been seriously injured and its strength has been reduced, this temperature also hurting the size in the paper, if it has been sized. In addltion the paper is still further weakened by '15 having its fibers pulled out in the direction of travel of the web, which does not permit them to dry as they were interlacedon the wire mesh of the paper machine during the process of forming the wet web from the pulp or stock.

' By my invention the strength of the paper may in some cases be increased about and a web or sheet is obtained which is approximatel as strong lengthwise'of the web 25 or sheet as across the web or sheet. This result is accomplished by my invention with a cheaper grade of stock than would be required to get the equivalent strength by the o old method.

or sheet of paper which will closely approximate hand made paper, which is the finest papermade. It will be better than loft dried paper.

In the manufacture ofordinary loft dried paper previously described the paper dries with its peculiar -cockeled effect which is demanded by the high class trade.

My improved method can be employed for either manufacturing high or low grade paper, or imitation hand made paper or imitation loft dried paper, having the same cockeled elfectas though the sheets had been cut, hung and allowed to dry slowly for forty-eight hours.

I have shown, by way of example, different forms of apparatus which may be employed to carry out my improved method.

In Figs. 1, 2, 3-and 4 the web of paper 1,

either coming from the wet end of a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper, is passed into and out of the vacuum chamber 2 so that the vacuum in the chamber will not be broken. I have shown this vacuum chamber provided with seals 3 and 4; in which I employ a liquid medium 5 of any. suitable material, which has no aflinity for,

and no deleterious effect upon, the sheet 1,

whatever it may be.

J The medium which I preferably employ is mercury though it is to be distinctly understood that any suitable medium, having the characteristics above mentioned, may be By my invention I get a very perfect'web employed. I may for example use an amalv gam, or an alloy, or any other suitable material which will satisfactorily seal the vacuum chamber 2 and permit the web of paper 1, passing into and out of said chamber 2, without being injured or affected in any manner and without breaking the vacuum.

Either or both the liquid seals 3 and 4 may be heated in any suitable manner, for example, by means of the steam pipes 100. Or. I may not heat the seals. In the latter case no steam or hot water would be passed through the steam pipes. These steam pipes 100 may be located in all the different seals shown in the drawings.

The degree of vacuum in the chamber 2 may be regulated. Preferably I employ a vacuum of about 2 8 inches of mercury, though this may be varied without departing from my invention. 1

The web 1 passes under the guide roll 7, in the seal 3, and thence over the guide roll 8, into a bath 9 of a heated medium which also has no affinity for, or de eterious effect upon, the web treated. I preferably use mercury as the heated bath 9, but a bath of any suitable medium may be employed, which will dry the web without injuring it or having any deleterious effect upon it. Such a bath might be made of an amalgam, or an alloy, or any other suitable material which has no affinity for the web treated and will'have no. deleterious eifect upon it.

This web 1 is fed through the bath 9 so that there will be but very slight tension upon it, not sufficient to prevent the fibers from shrinking at will or at random while passing through said bath. Preferably I pass the web 1 of the material under the submerging rollers 10, 10 and over the guide rollers 11, 11. This bath may be heated in any suitable manner as by the steam pipes 12, 12, though it is to be understood thatany suitable heating medium may be used to heat the bath 9. The web is then withdrawn from the vacuum chamber 2, through the second .seal 4, under the guide roll 13 and over the guide roll 14;, and is then preferably rolled or reeled into the finished roll 15.

The vacuum chamber is provided with pipes 16, 16 which are connected with any suitable form of vacuum apparatus to maintain the vacuum desired within the vacuum chamber and withdraw the moisture and air given off by the web 1. The vacuum chamber is also preferably provided with any suitable form of windows 17 ,17.

W hen the sheet material is a web of paper, from which imitation hand made or imitation loft dried paper is to be made, the web.

1 will be taken from the wet end of the paper machine or from the sizing vat and then passed through the vacuum chamber 2 in the manner previously described. While drying, the fibers will shrink at will or at random, there not being suflicient tension upon the web 1 to prevent this action. The drums 10, 10 are relatively so small that they will practically not reduce the cockle upon the web of paper, so that when the web paper the 'fibers' of the paper were both,

when they were originally dried before being sized, and also after being sized, permitted to dry at random, or while not under sufiicient tension to revent them fromv shrinking at will, b'emg substantially as a formed on the wire mesh of the paper machine. In manufacturing imitation loft made or loft dried paper and immediately roll it into the roll 15, which is the most dried paper the fibers, if the web' was first dried over a plurality of steam cylinders or dryers, as in common. practice, would -be somewhat stretched in the direction of the travel of the web overthedrymg cylinders or drums.

I then take theweb of imitation hand economical manner of handling such paper.

' Each layer of paper, on the complete roll,

, protects all other layers of paper under it.

' sheets incident to their handling.

This is not so true, of course, when the web is cut into sheets and stacked as in regular loft dried papeiz' It will therefore be'obvious that instead of the labor of cuttingthe sheets and stacking them, as in the ordinary process of making loft dried paper-together with the delay of forty-eight hours for drying, thatby my improved method I can make, in the few minutes required to run the web through the vacuum chamber, imitation loft dried paper, which will be stronger and better and have all the advantages of regular loft dried paper including the cockeled effect. Further the resulting product can be rolled mto a roll [0f finished loft dried paper, which is the most convenient andeconomic way of handling it as previously explained avoid:

ing' the liabilityto damage the separate The dry web can then be calendered in a stack calender'rat-her than in a sheet calender at a much less cost.

In some cases instead of having two liquid seals 3 and 4, I may employ simply one seal 18, Fig. 2. In this modification of my nvenaction upon the' surface of the with a hollow'member 20, which dips into the sealing-member 21. In this form the web..1 is-fed into the vacuum chamber" over the guide roll 22,'under the submerging roller 23, over the roll 24, thence under the submerging rollers 25, 25 in the bath .9, and

.over the rollers 26, 26, thence over the guide rollers 27, 28 and under the submergin roll- -ers 29, 29 and over the rollers 30, 30, t ence over the roller 33 and-out under the, roller 34 andover the roller 35 where the web 1 of the finished product may be rolled into a roll or reel 36. -In this formof my invention thesealing' j -inedium 5 may bejust the same as in the other form. This. is'also'true .of the material of the bath 9.

The 'constructionshown in Figs. 1 and 2 will -ve an imitation'loft dried paper having t e maximum cockeled efiect, as the roll 10, 11-, 26, 27, 29 and 30 are relatively so small that they will have-no smoothing 'I may, however, vary this rollers or heatin drums 37, 37 in the vacuum chamber .38, ig. 3.1 The web l-passin paper y placing over the guide, rollers 41 41 and these r0 ers 37, 37, whichare ativelylarge, will glve a smoother surfaceto the open These rollers 37 may be steam heat or otherwise heated, or'not heated at. all as found convenient or expedient. The bath9 and'the sealing medium 5 are the same in this form as in that previously described.

In some cases it may be desirable to ob tain a sheet having a cockeled surface intermediate between that formed by the small rollers in Figs. 1 and larger drums in Fig. 3. f Y

I'have' shown in' Fig. 4 a vacuum chamber 39, having guiderollers 41,41 and rolls 40, 40 which while larger than the rollers 10, 10 in Fig. 1 are not so large as the rolls or drums 37 in Fig. 3. In this form the web 1 will pass through the vacuum chamber with a more or less cockeled efi'ect, but will have .a less cockeled effect than the web which passes through the vacuum chamber of Fig. 1. The drums 40, 40 will tend to lessen the cockel of the paper as they are larger than the drums or rollers 10 of Fig.- 1. By varying the \cockeled effect different demands in the trade can be met.

I may em 10y different apparatus, as shown in the drawings, to obtain thesevarious degrees of cockeled paper, or I may rearrange the different rollers in one apparatus to obtain these differences in the cockeled effect 'on the paper being treated.

The bath 9 and sealing medium 5, 5 are the same in this as in the other construction. The temperatures of the bath 9 may vary. Preferably it is heated to such a temperature as to insure the boiling of the water in' the (web 1 at a very low -temperature. This 2, and the relatively tion the vacuum chamber .19 is provided temperature may vary. Excellent results may be obtained with a vacuum of 28 inches and the bath 9 at 200 F. It is to be distinctly understood, however, that this temperature and vacuum are given simply as an example for the temperature may be increased or de creased. This applies also to the vacuum. Itis desirable, however, to get as near a perfect vacuum as possible. With a high vacuum and the bath 9 at a temperature, as high or higher, than that above given, the web of sheet material is very quickly dried, and the fibers of the paper will not be marred, distorted, warped or injured in any particular. On the contrary the fibers will be substantially as laid upon the wire mesh in the paper machine during the process of making the wet web of paper.

At a vacuum of 28 inches of mercury water boils at a temperature of approximately 100 F. If the mercury bath were at a temperature of 200 the difference in temperature between the bath and the boiling point of the water in the paper would be 100 and, as the water would evaporate at 100 F., the paper would necessarily be dried when this temperature was raised to above 100 F. With the liquid bath at a temperature of approximately 200 it will readily be seen that the paper would be dried very rapidly. It is understood, of course, that the paper is preferably passed through the drying machine at such a speed that. as soon as the water in the paper is evaporated the paper.

passes out of the machine and hence the paper never reaches a temperature of much over 100 F. Should there be any reason to run the paper at a slower speed, I would preferably either reduce the temperature of the liquid bath or lower the vacuum or both, depending upon circumstances.

By rolling the finished web of drying paper into rolls-not in sheets as in loft dried paper-I can calender my dry web in a stack calender rather than'in a sheet calender with the resulting saving in cost of manufacture. I C

Instead of drying the web by passing it through a liquid bath in the vacuum chamber, as previously described, I may dry it in any other suitable manner that permits the fibers of the paper to dry without being substantially rearranged from the interlaced position that they assumed on the wire mesh of the paper machine, resulting in aweb of paper as strong lengthwise of the web as crosswise of said Web.

In Fig. 5 and Fig. 6 I have shown two modifications of my invention in which the wet web of paper is ,passed continuously through the vacuum chamber adjacent to, put not in contact with, fixed steam radiaors.

The web 1 is fed into the vacuum machine over the guide roll 51, under the submerging roll 52, over guide roll 53, and under the guide rolls 54, 54 and over the guide rolls 55, 55. While passing through the vacuum chamber 2, it is put under little or substantially no tension; the tension is sufficient merely to pass the web through the onefor each loop, though of course. this arrangement may be varied without departing from my invention. These heated surfaces a-re heated in any suitable manner, such as by steam either at high or low pressure. In some cases hottwater may be used to heat them, or exhaust steam or they may be heated in any other suitable manner. Excellent results may be obtained-= by heating the radiators 5T, 57 to about 22891 and have the vacuum at about 28 inches. It is to be distinct-ly understood, however, that this temperature and vacuum are given simply as an example for the temperature may be increased or decreased. This applies also to the vacuum. It is desirable to get as near a perfect vacuum as possible. The moisture in the paper or other sheet material is converted into steam at very low drying temperatures so that the texture, or fiber of the sheet material, or paper, will not be marred, distorted, warped or injured in any particular.

The radiators 57, 5.7 should preferably be arranged in the vacuum chamber so that the folds 56 of the web 1 of the sheet material will pass very close to, but not come in contact with them. If this sheet material is a web of paper, for example, and should touch one of the radiators 57, the web is apt to stick, which might cause the web to tear or otherwise foul the apparatus. Of course, if the radiators 57, 57 are heated with steam and the web should touch a radiator, the water in the web would instantly be converted into steam which would blow or free the web from the radiator. To avoid any liability of the web touching the radiators, I therefore leave suflicient clearance to perin it free passage of the sheet material. To get the best results the radiators 57 should be located as close as convenient to the loops 11 without the liability of the sheet material touching them on its Way through the vacuum chamber: I

The web of paper 1 passing through the vacuum chamber will in this manner be dried, without placing any appreciable tension upon the web. What tension there is upon the web, as previously described, is merely sufficient to pass it through the vacuum chamber and this tension does not appreciably interfere with the fibers of the paper drying substantially as they were formed on the wire mesh of the paper machine, or as here termed at random flso that the result.-

' ing' sheet of paper is approximately as strong lengthwise of the sheet as it is crosswise.

drying of the web within the vacuum chamber adjacent to, but not in contact with, the

- radiators 57, 57 and while under no appreciable tension causes the sheet or Web to dry with the cockeled effect of genuine hand made and loft dried paper. v The dry web of paper ,1, whether it be high, or low grade" paper or imitation hand i made paper or imitation loft'dried paper,

.under the submerging roller 58, over the guide roller 59, and is then preferably wound into a roll of finished paper 60.

In some cases I may use one seal insteadof two. I have shown such a construction in Fig. 6, in which the vacuum chamber-61 is provided with the'same radiators 57, 57 and thesame guide rollers 54, 54 and 55, 55. Connected to the vacuum chamber is a hollow member 62, which dips into a liquid sealing member 63. The liquid 5 in this sealing member is the same as in the seals 3 and 4 of Figs. land 5.

The web 1 i submerging roll 65 and over the guide roll 66, and, thence as indicated by the arrows, over and'under the guide rolls 54, 54 and 55, 55 ,on the left of said figure, then .over

the guide roll 67 to the guide roll 68, mounted at the other end' of the vacuum chamber,

thence over and under the set of guide rolls 54, 54 and 55, 55 mounted on the right of said figure, all as indicated by the arrows, -thence over the guide roll 69'jand out of said vacuum chamber through the liquid' seal I 64-under the submerging roller '70 over the nected to any suitable vacuum apparatus to maintain the desired vacuum chamber.

When the sheet material is a web :of

vacuum within the paper, from which imitation "hand 'made' paper or imitation loft dried paper is to be made, the web 1 is taken from the wet end of the paper machine or from the sizing vat and thenpassed through the vacuum chamher in the manner previously described.

When it emerges over the rollers 59'or 71, it

is dry, very strong, bein substantially as strong lengthwise of the 5 eat as it-is cross- In making imitation loft dried paper, this fed into the vacuum chamber-61 over the guide: roll 64 and under the wise of the sheet and has the same coekeled? effect as regular hand made or loft dried paper. It will be stronger than loft dried paper, however, for the reason that the fibers of the ,paper, as they originally came from the wet end of. the paper-machine in the form of a wet web of pa er, were preferably dried by my metho prior to being sized. The fibers of the paper were therefore,-b'oth when they were originally dried before being sized and also after being sized,-permitted to dry or shrink at random, and while not under sufiicient tension to prevent them from so doing.

In Figs. 7 and 8 I have illustrated amodiadjacent to a glowing element, as the resistance coil of an electric heater. v The web 1 is fed into the vacuum machine over the guide roll 51, underthe submerging fication of my invention inwhichI dry the web in the vacuum chamber by passing it roll 52, over guide roll 53, and under the guide rolls 54, 54and over the guide rolls 55, 55.. While passing-through the vacuum chamber2, it is put under little or no tension;'the tension is suflicient merely to pass the web throu h thechamber. Preferably, the web is fe through in folds or loops Adjacent to the loops 56, 56 but not in contact with them, I mount one or more glowing-members preferably in the form of electric heaters 73, 73. Preferably these electric heaters are mounted between the folds or loops 56, 56 as indicated in Fig. 7., but of course this arrangement may be variedwit out departing from- .my-invention. The e'lec ;ric.heaters 7 3 are connected to the bars 7 3, from which extend the 'wires 73", through the insulated packing 73, to. the

contact terminals 7 3. .The distance between.

the folds 56,56 and the electric heating mem:

bers 73, 7 3 must be suflicient te; ,permit free passage of the web of paper without comic heating eleing in contact with the electiments. V

To insure mlnimum tension uponithe paper "during drying, I may use any ordinary means to decrease the tension: d'uy moving thepaper, as for example, by mount.--

in the venous rolls, irf each of the forms illustrated, in ball bearings, and driving them by a friction device whereby the speed of the rolls may be regulated. One form of such device is illustrated in Fig. 10 wherein the rolls such as roll 54 is mounted in ball bearings'contained in the housing 101, held in through the wall 2 of the vacuum chamber. The pulley 103, preferably made of bronze,

place by suitably packed bolts 102 passing is mounted on, and revolves on, the shaft 104 of the roll 54. The 104 upon which the p ey is mounted, is preferably made of babbitt metal. Secured to the end-of roll 54 land the side of the ortion of the shaft pulley 103 are two friction discs 105 and 106, made of any suitable material such as leather or woven asbestos tape. The pulley 103 is driven at constant speed by a belt 107. The small roll 108 is mounted in a housing 109, the position of which is regulated by the lever 110, actuated by the rod 111, pass ing throu h the packing gland 112 in the wall 2. Tie position of the rod 111'is regulated by the nut 113. The other end of the roll 54 will be mounted in a ball bearing housing similar to 101. The speed of roll 54 may be regulated, or itsspeed may be varied from a similar roll, by varying the pressure between the discs 105 and 106 by applying more or less pressure between the roll 108 and the pulley 103, which is driven at constant speed. As the friction between the discs 105 and 106 increases, the more nearly will the speed of roll 54 approach that of pulley 103.

'The web of'paper passing through the vacuum chamber will in this manner be dried, without placing any appreciable tension upon the web. \Vhat tension, as previously described, there is upon the web is merely suflicientto pass it through the vacuum chamberand this tension does not appreciably interfere with the fibers of the paper drying at random, so that the resulting sheet of paper is as strong lengthwise of the sheet as it is crosswise.

In making imitation loft dried paper, this drying of the web within the vacuum cham- "ber adjacent to, but not in contact with, the

electric heaters 73, 73 and while under no appreciable tension causes the sheet or web to dry with the cockeled effect of genuine hand made and genuine loft dried paper.

The dry web of paper 1, whether it be high or low grade paper or imitation loft dried'paper, after passing between the different electric heaters 73, 7 3 is fed over the guide roller 57, and out of the vacuum chamber through the seal 4 under the sub-- merging roller 58, over the guide roller 59, and is then preferably wound into a roll of finished paper 74.

In some cases, I may use one seal instead of two. I have shown such a construction in Fig. 8, in which the vacuum chamber 61 is provided with the same electric heaters 73, 73 and the same guide rollers 54, 54 and 55, 55. Connected to thevacuum chamber is a hollow member 62, which dips into aliquid sealing member 63. The liquid 64 in this sealing member is the same as in the seals 3 and 4.

The web 1 is fed into the vacuum chamber 61 over the guide roll 64 under the subat the other end of the vacuum chamber,

thence over and under the set of guide rolls 54, 54 and 55, 55 mounted on the right of said figure, all as indicated by the arrows. thence over the guide roll 69 and out of said vacuum chamber through the liquid seal 64 under the submerging roller 70 over :the guide roll 71, and is then preferably wound into the complete dry finished roll of sheet material 75. The drying action in connection with the vacuum chamber 61 is the same as the drying action 1n vacuum chamber 2.

The drying capacity of the fixed steam radiators shown in Figs. 5 and 6 varies in an electric incandescent bulb.

The action on the web of paper passing through the vacuum chambers in Figs. 7

and 8 is in all respects similar to the action on the web of paper passing through the vacuum chambers shown in Figs. 5 and 6.

It is, of course, to be understood that the different rollers 10, 11, 25, 26, 3'7, 40, 41, 54 and 55 may be driven or not as desired; that doors are used to permit cleaning of the vacuum chamber and for rethreading of the machine should this become necessary; and that any feeding mechanism may be used if desired. The bath 9 in Figs. 3 and 4 may be heated in any suitable manner; as for example by a steam jacket 50, or in any other manner that may be found convenient or expedient.

In making imitation hand made paper the web is dried in my vacuum machine as it leaves the wet end of the paper machine; it is then tub-sized and then again redried in my vacuum machine.

In the manufacture of imitation loft dried paper the web may be first dried on the ordinary form of multiple steam. driers or cylinders now in common use, then tubsized, and then dried in my vacuum machine rather than in a drying loft as at present.

It will therefore be seen that in my imitation hand made paper the fibers of the paper are never appreciably stretched but remain approximately as they were formed into a web upon the wire mesh of the paper machine. In the manufacture of imitation loft dried paper, if the web is first dried over a plurality of exposed drying drums or cylinders as now in common practice, the fibers will be stretched more or less in the direction of travel of the web.

It is common practice in some cases where certain results are desired to roll the wet Web of paper into a roll or reel after leaving the sizing vat of the paper machine and allow it to stand in these rolls for a certain length of time to allow a chemical action to take place in the size and in the paper. Frequently the rolls are covered with wet cloths to prevent the ouside layer of the paper drying too rapidly. 'After the wet roll of paper has been allowed to stand for what has been determined the correct time, the wet web of paper from these rolls may then be dried by my method.

,To insure that there shall be but the minimum tension thrown upon the web of paper as itis dried in my apparatus 1' may use any ordinary means to lessen ,the tension on r the web, as for example, by having the different rolls mounted on ball bearings. I may also drive these rolls by some friction device whereby the speed of the-rolls may be regulated to insure that there will be but little or no tension on the web while it is drying. The tension will be regulated so as to prevent the fibers of the paper substantially rearranging themselves from the position that they assumed on the wire mesh of the paper machine.

Having pointed out the many advantages of my method and apparatus over those here'- tofore used, it will be apparent that the use of my invention results in great economy in the initial cost of apparatus and in large savings in cost of operation, maintenance and repairs.

Having thus described this invention in connection with several illustrative embodiments thereof, to the details of which I do not desire to be limited, what is claimed i as new and what is desired to secure by Lotters Patent is set forth in the appended claims.

What I claim is i 1. The method of drying a continuous web of sheet material consisting in con-' tinuously heating and drying it in a vacuum while under little or no tension.

2. The method of drying a continuous web of sheet material consisting in passing it continuously ;in folds or loops throu h a vacuum chamber Without breaking t e vacuum and with only suificient tension upon the sheet material to feed it through said vacuum chamber and heatingone or more of the folds or loops.

.3. The method of drying a wet web of paper consisting in passing the wet web continuously into a vacuum chamber without breakin the vacuum, continuously drying 'said we in the vacuum chamber without placing sufficient tension 'upon the web to cause the fibers of the paper to substantially rearrange themselves from their: interlaced position formed on the wire mesh of the paper machine, thereby obtaining a dry web of paper substantially as strong lengthwise of the web as crosswise of the web, and continuously withdrawing the dry Web from the vacuum chamber without. breaking the vacuum.

4. The method of drying a wet web of of paper substantially as strong lengthwise of the web as crosswise of the web, and continuously withdrawing the dry web from the vacuum chamber without breaking the vacuum and immediately rolling the dry web into a roll of reel of finished paper.

5. The method of'drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper, into and out of a vacuum chamber through one or more liquid seals that have no affinity for or deleterious effect upon said web, and continuously heatingand drying said web of paper in said vacuum chamber, and subjecting the web to only sufficient tension to feed it through the vacuum chamber and not substantially rearrange its fibers as laid on the-wire mesh of the paper machine, thereby forming a Web of paper substantially as strong lengthwise of the web as crosswise of the web.

6. The method of drying a wet web of paper consisting in co-ntinuously feeding the wet web of paper directly from the wet end of a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper, into and out of a vacuum chamber through one or more liquid seals that have no aflinity for or deleterious effect upon said web, feeding said web through the vacuum chamber in folds or loops, heating one or more of said folds or loops, and subjecting the web to only sufficient tension to feed it through the vacuum chamber and not substantially rearrange its fibers as laid ,on the wire mesh of the paper machine, there by forming a web of paper substantially as strong lengthwise of the web as crosswise of the Web.

7 The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine, or from a; sizing vat, or from a coloring apparatus, coating machine or printing machineor directly from liquid hat a roll of wet paper, into and out of a vacuum chamber through one or more liquid seals that have no afiinity for or deleterious effect upon said web, feeding said web through a bath of a heated liquid in said vacuum chamber, said liquid having no affinity for or deleterious effect upon said web and subjecting the web to only sufficient tension to feed it through the vacuum chamber and not substantially rearrange its fibers aslaid on the wire mesh of the paper machine, thereby forming a web of paper substantially as strong lengthwise of the web as crosswise of the web.

8. The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wetpaper, into and out of a vacuum chamber through one or more liquid seals that have no ailinity for or deleterious efiect upon said web, feeding said web through a heated liquid metal bath in said vacuum chamber, the metal of the liquid bath hav-* ing no affinity for or deleterious effect upon said web, and subjecting the web to only suflicient tension to feed it through the vacuum chamber and not substantially rearrange its fibers as laid on the wire mesh of the paper machine, thereby forming a web of paper substantially as strong lengthwise of the web as crosswise of-the web.

9. The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine, or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper, into and out of a vacuum chamber throu h one or more liquid seals that have no a nity for or deleterious effect upon said web, feeding said web through a heated bath of mercury in said vacuum chamber, and subjecting the web to only sufficient tension to feed it through the'vacuum chamber and not substantially rearrange its fibers as laid on the wire mesh of the paper machine, thereby forming a web of paper substantially as strong lengthwise of the web as crosswise of the web.

10. The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine'or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper into and outof a vacuum chamber through one or more liquid seals that have no aflinity for or deleterious effect upon said web, assing said web through a heated ii in the vacuum chamber, the liquid of said bath having no affinity for or deleterious efiectupon said web, and giving the surface of the web as it passes through said heated liquid bath a more or less cockeled efl'ect.

11. The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine or from a sizing vat, or from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper into and out of a vacuum chamber throu 'h one or more liquid seals that have no a nity for or deleterious effect upon said web, passing said web through a heated liquid metal bath inthe vacuum chamber, the metal of said bath having no aflinity for or deleterious effect uponsaid web, and giving the surface of the web as it passes through said heated liquid metal bath a more or less cockeled effect.

12.'The method of drying a wet web of paper consisting in continuously feeding the wet web of paper directly from the wet end of a paper machine or from a sizing vat, 01' from a coloring apparatus, coating machine or printing machine or directly from a roll of wet paper into and out of a vacuum chamber through one or more liquid seals that have no affinity for or deleterious effect upon said web, and continuously pass ing said web through a heated mercury bath in said vacuum chamber and giving the surface of the web, as it passes continuously through the heated mercury bath, a more or less cockeled effect.

13. An apparatus for continuously dry ing a web of sheet material comprising a vacuum chamber, one or more liquid seals for said vacuum chamber the liquid of said seals having no affinity for or deleterious effect upon said web1of sheet material and means in said vacuum chamber toheat and dry said web without substantially rearranging its constituent elements.

14:. An apparatus for continuously drying a web of wet paper comprising a vacuum chamber, one or more liquid seals for said llO vacuum chamber the liquid of said. seals having no aflinity for or deleterious effect upon said web of wet paper, and means in said vacuum chamber to heat and dry said web of paper withoutsubstantially rearranging its fibers as laid upon the wire of the paper machine.

15. An apparatus for continuously drying a web of wet' paper comprising a vacuum chamber, one or more'liquid seals for said vacuum'chamber, and a heated liquid bath in-said vacuum chamber, said bath and liq-. uid seal .or seals having no afiinity foror deleterious effect upon the web of paper, one or more cylinders mounted'in the heated liquid bath, to give a more or less cockeled surface to the web of paper.

OGDEN MINTON. 

